This is an extremely rare scarab for the king Ammu (Aamu).
The scarab is inscribed for "the son of Ra, Ammu, given life“

There are only 30 scarabs known with his name.
See:
K. S. B. Ryholt: The Political Situation in Egypt during the Second Intermediate Period
(= The Carsten Niebuhr Institute Publications. Vol. 20). The Carsten Niebuhr Institute of Near Eastern studies,
Kopenhagen 1997, S. 43, 364-66 (File 14/4)